High-frequency telegraphy and telephony system



July 16, 1929. p, A 1,721,236

HIGH FREQUENCY TELEGRAPHY AND TELEPHONY SYSTEM Filed Sept. 12, 1925 IIIIIII- N E 2 d M N E,

bJlJ/Wf/VVJJ INVENTOR AUL T'TZ A ORNEY Patented July 16, 1929.

F BERLIN, GERMANY, ASSIGNOR TO GESELLSCHAFT DRAHTEL OSE TELEGRAPHIE M. '3. st, or BERLIN, GERMANY, a coaronarmn 0F GERMANY;

HIGH-FREQUENCY TELEGRAPHY AND TELEPHONY SYSTEM.

Application filed September 12, 1925, Serial No. 55,893, and in Germany September 26, 1924.

My invention relates generally to high frequency telegraphy and telephony communication and more specifically to the establishing of communication between a central dispatching station in a railroad shifting yard and the various shifting locomotives out upon the track system."

My invention has for an object to increase the traffic capacity of a railway system and to do so by means of establishing a better communication system between the dispatcher and the engine-men operating the locomotives of the railway system, the communicati on system being a high frequency telephony or telegraphy system.

Another object of my invention is to construct such a system involving a structure of operatable simplicity and of such a nature as not to interfere with other systems of communication and also to be within reasonable cost of commercial construction.

It is a further object of my invention to.

design a system so that simple and interchangeable transmission and receiving units may be utilized which units operate at the expenditure of low energy.

It is still another object of .my invention to provide a safety means or means for indieating the condition of the operation of the signalling apparatus so that a failure of the apparatus may immediately be detected Further objects will be apparent upon consideration of the following disclosure made herein taken in connection with the drawing which is a diagrammatic representation of the invention.

In view of the steady growth of traflic in railway stations and terminals, thev question arises as to whether it would be more suitable to meet thegrowing traflic demands by enlarging the station, or else by-providing and adopting more improved and up-to-date technical arrangements for supervising the increased trafiic; For example, in the ease of freight traffic, the station space to be provided may be so much smaller, if better means are adopted for the distribution of the freight cars, and the assembly of freight trains.

For the purpose of shunting service, usual- 9. number of engines are in operation, and certain times they are scattered all over the station, so that difiiculties are encountered in directing them just to the points where they are most required. For this reason, the

general set of connections and layout of my number of'engines pressed into service to do the shunting work is greater than absolutely necessary, which means that'the engines are not fully utilized.

Speaking generally, no means are available for transmitting orders to such locomotives. For the object of facilitating the work at the humps certain devices have been adopted I in order ,to transmit or impart working instructions and orders to the engines which shift the freight train to 'be distributed up the incline or hump. What is used are the well-known optical arm signals, and more recently, electrical devices whereby acoustic signals are sent to the locomotive electrically through the rails, being rendered intelligible on the engine through means supplied through a sliding loop or how.

Now, the problem here dealt with could alsobe solved by working with space-radiating 75.

high frequency telephony or telegraphy. This ofiers the great disadvantage, however, that large sending energies have to be worked with, with the consequence that great trouble maybe occasioned in other radio communication work, not to speak of the fact that such sending means are complicated both in attendance and'mainte'nance.

The advantages residing in high frequency service, in the sense of the present application, can be utilized also in that certain groups of tracks or-rails laid near a station are equipped with air lines which in the case ofbut one central commanding or order-distributing point, are united with the latter. This line system is energized by a high frequency generator. The high frequency currents which are setup on the air-line system, in the case of telephonic order transmission, serve as carriers for speech which is impressed upon the generator in electrical form. The engines themselves are equipped with very simple receiving devices adapted to high frequency telephony or telegraphy. I

This is illustrated diagrammatically in the drawing where Figure 1 shows schematically the transmitter and receiver of the central dispatching station coupled to the radio frequency air line system, and Figure 2 illustrates the apparatus mounted on'eachloco- 05 motive for cooperating with the air line system and establishing communication with the central station. A high frequency telephony 1 line 1 is strung over the track system supported by insulators 2 and has inserted in series 2 are therewith near its dead end an absorption resistance 3 for the prevention of reflection and to render the air line aperiodic in nature. The line system is energized by a high frequency source and transmitter coupled to the line indicated generally by 4, the power sup-' ply for said transmitter being indicated by the A. C. and D. C. sources for the cathodes and anodes of the vacuum tubes, respectively. The high frequency generator is constantly modulated by a common buzzer 5 or some other well-known means until it is desired to transmit a message at which time the modulating means is either manually or automatically cutout.

A receiving apparatus may also be, coupled to the same end of the air line system to make it possible to receive the messages sent from instruments coupled to the other end of the air line.

Each locomotive of the railway system is equipped with a loop or other coupling means as 6 to which may be coupled either a receiving apparatus or a transmitting apparatus indicated by 7 and 8 respectively or both. From the above it can be seen thatcommunication may be established between 5O system, the system can be rendered aperiodic a central station and a plurality of substations such as locomotives out on the tracks."

In case of intelligence transmission" from the locomotives to a central control point, an air-line system thus built above the station offers corresponding advantages. The desired end may be obtained by very simple readily interchangeable, mountable and de mountable antenna devices and transmitters of low energy on the engines.

In the instance of establishing communication at hump sections, the said air-line system is limited to one overhead line installed above a group of tracks by the described means, the utilization of such an overhead line system being made possible alsofor several independently operated telephony arrangements between the station and several engines.

The advantages offered by such a method are quite plain. In order to improve the propagation of the high frequency currents throughout the station, and to promote the adaptation of the generator to the air-line 1n nature'by any convenient means, for instance, by the connection of resistance to prevent reflection at the ends of each branch of the line and thereby eliminate a serious diiiiculty prevalent in all high frequency telephony systems.

The electrical equipment in railway working is generally based upon the closedrcircuit principle. In this manner with the additional aid of suitable means care is taken so that failure of the apparatus will cause no danger. In the case of switching service, the demand will therefore arise that the failure or inoperation of the telegraphic or telephonic connection of choke-coil chains which are connection between engine and order point may be rendered perceivable, in order that the engine busy in switching work may be stopped at once.

In the case here dealt with, the problem can be solved in the following way: the high frequency transmitter is provided with a modulating device 5 which is brought to act upon the transmitter as long as no orders are being sent out. The proper function and operativeness of the transmitter can thus be acoustically controlled in the telephone receiver. Whenever orders have to be transmitted, the modulating means is disconnected, while the normal telephony connection is rendered op erative. For the object of modulating the transmitter, rhythmic interrupters and the like can be used. A very simple meansfor modulation consists of the connection and disgenerally used in telephony transmitters for the purpose of eliminating noise. due to lines.

In case of high frequency communication by means of pie-arranged signals which are to be reproduced by the receiver either by acoustic or optical means, the receiver can be provided with convenient additional signalling means such as disclosed at 5 adapted to indicate failure of the communication, i. e., the interruption of the-high frequency excitation of the receiver apparatus from the transmitter.

Having described my invention, what I desire to secure by Letters Patent is 1. In a railway communication system for use in establishing communication with locomotives on various tracks, a high frequency overhead line system distributed overthe tracks, said line system being excited by a high frequency carrier current, receiving and transmitting means mounted upon the locomotives adapted to cooperate with said overhead line system and means for continuously modulating said carrier current to produce audible sounds in the receiving apparatus when intercommunication is not being carried on.

2. In a railway communication system for use in establishing communication with locomotives on various tracks, a central dispatch- 5 ing station provided with transmitting and receiving means, a high frequency overhead line systemdistributed over the tracks inductively coupled to said transmitting and receiving means and excited by a high freo quency carrier current, receiving and transmitting means mounted upon the locomotive adapted to cooperate with said overhead line system, and means associated with the transmitting means at the central station for continuously modulating said carrier current to produce audible sounds in the receiver.

3. In a high frequency system of intercommunication between a central dispatching station and a plurality of locomotives on various m tracks, transmitting and receiving means associated with the central station and with each locomotive, and means associated with the transmitter at the central dispatching station for producing an audible signal at the receiver of the locomotive when commun cation has ceased, to indicate eificient operativeness of the system.

4. In a high frequency system of intercommunication' between a central dispatching station and a plurality of locomotives, a high frequency overhead line system distributed over the tracks and energized by a high frequency carrier current, receiving and transmitting apparatus inductively coupled'to said line system, receiving and'transinitting apparatus also mounted upon the locomotives and adapted'to cooperate with said'overhead line system, and meansassociated with the transmitter at the central station adapted to be cut out of use in the normal operation of the system, and when out in to continuously modulate the carrier current to produce audiblesounds in the receiver, thereby indicating the operativeness of the system.

5. In a high frequency system for signalling between a a central dispatching sta tion and a moving train, each being provided with transmitting and receiving apparatus,

the method of indicating efficient operation between station and train, which consists in continuously modulating the high fre quency carrier Wave at the central transmitter to indicate an audible response in the train receiver, said continuous modulation. occurring'during intervals when modulation by speech currents for signalling purposes it not taking place.

PAUL TATZ. 

